<template>
  <div class="Progress">
    <el-progress
      v-if="hasStatus"
      :type="type"
      :status="status"
      :stroke-width="strokeWidth"
      :stroke-linecap="strokeLinecap"
      :text-inside="textInside"
      :width="width"
      :show-text="showText"
      :color="color"
      :percentage="displayValue"
    />
    <el-progress
      v-else
      :type="type"
      :stroke-width="strokeWidth"
      :stroke-linecap="strokeLinecap"
      :text-inside="textInside"
      :width="width"
      :show-text="showText"
      :color="color"
      :percentage="displayValue"
    />
  </div>
</template>

<script>
import { requestAnimationFrame, cancelAnimationFrame } from './requestAnimationFrame.js'
export default {
  props: {
    type: {
      type: String,
      default: 'line',
      validator: val => ['line', 'circle', 'dashboard'].indexOf(val) > -1
    },
    status: {
      type: String,
      default: '',
      validator: val => ['success', 'exception', 'warning', ''].indexOf(val) > -1
    },
    strokeWidth: {
      type: [Number, String],
      default: 6
    },
    strokeLinecap: {
      type: String,
      default: 'round'
    },
    textInside: {
      type: Boolean,
      default: false
    },
    width: {
      type: Number,
      default: 126
    },
    showText: {
      type: Boolean,
      default: true
    },
    color: {
      type: [String, Array, Function],
      default: ''
    },
    startVal: {
      type: Number,
      required: false,
      default: 0
    },
    endVal: {
      type: Number,
      required: false,
      default: 2017
    },
    duration: {
      type: Number,
      required: false,
      default: 3000
    },
    autoplay: {
      type: Boolean,
      required: false,
      default: true
    },
    decimals: {
      type: Number,
      required: false,
      default: 0,
      validator(value) {
        return value >= 0
      }
    },
    useEasing: {
      type: Boolean,
      required: false,
      default: true
    },
    easingFn: {
      type: Function,
      default(t, b, c, d) {
        return c * (-Math.pow(2, -10 * t / d) + 1) * 1024 / 1023 + b
      }
    }
  },
  data() {
    return {
      localStartVal: this.startVal,
      displayValue: this.formatNumber(this.startVal),
      printVal: null,
      paused: false,
      localDuration: this.duration,
      startTime: null,
      timestamp: null,
      remaining: null,
      rAF: null,
      hasStatus: ['success', 'exception', 'warning'].indexOf(this.status) > -1
    }
  },
  computed: {
    countDown() {
      return this.startVal > this.endVal
    }
  },
  watch: {
    startVal() {
      if (this.autoplay) {
        this.start()
      }
    },
    endVal() {
      if (this.autoplay) {
        this.start()
      }
    }
  },
  mounted() {
    if (this.autoplay) {
      this.start()
    }
    this.$emit('mountedCallback')
  },
  destroyed() {
    cancelAnimationFrame(this.rAF)
  },
  methods: {
    start() {
      this.localStartVal = this.startVal
      this.startTime = null
      this.localDuration = this.duration
      this.paused = false
      this.rAF = requestAnimationFrame(this.count)
    },
    pauseResume() {
      if (this.paused) {
        this.resume()
        this.paused = false
      } else {
        this.pause()
        this.paused = true
      }
    },
    pause() {
      cancelAnimationFrame(this.rAF)
    },
    resume() {
      this.startTime = null
      this.localDuration = +this.remaining
      this.localStartVal = +this.printVal
      requestAnimationFrame(this.count)
    },
    reset() {
      this.startTime = null
      cancelAnimationFrame(this.rAF)
      this.displayValue = this.formatNumber(this.startVal)
    },
    count(timestamp) {
      if (!this.startTime) this.startTime = timestamp
      this.timestamp = timestamp
      const progress = timestamp - this.startTime
      this.remaining = this.localDuration - progress

      if (this.useEasing) {
        if (this.countDown) {
          this.printVal = this.localStartVal - this.easingFn(progress, 0, this.localStartVal - this.endVal, this.localDuration)
        } else {
          this.printVal = this.easingFn(progress, this.localStartVal, this.endVal - this.localStartVal, this.localDuration)
        }
      } else {
        if (this.countDown) {
          this.printVal = this.localStartVal - ((this.localStartVal - this.endVal) * (progress / this.localDuration))
        } else {
          this.printVal = this.localStartVal + (this.endVal - this.localStartVal) * (progress / this.localDuration)
        }
      }
      if (this.countDown) {
        this.printVal = this.printVal < this.endVal ? this.endVal : this.printVal
      } else {
        this.printVal = this.printVal > this.endVal ? this.endVal : this.printVal
      }

      this.displayValue = this.formatNumber(this.printVal)
      if (progress < this.localDuration) {
        this.rAF = requestAnimationFrame(this.count)
      } else {
        this.$emit('callback')
      }
    },
    formatNumber(num) {
      return parseFloat(num.toFixed(this.decimals))
    }
  }
}
</script>
